21499879 has 2 divisors, whose sum is σ = 21499880. Its totient is φ = 21499878.

The previous prime is 21499873. The next prime is 21499889. The reversal of 21499879 is 97899412.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21499879 - 2⁹ = 21499367 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21499873) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10749939 + 10749940.

It is an arithmetic number, because the mean of its divisors is an integer number (10749940).

Almost surely, 2^21499879 is an apocalyptic number.

21499879 is a deficient number, since it is larger than the sum of its proper divisors (1).

21499879 is an equidigital number, since it uses as much as digits as its factorization.

21499879 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 326592, while the sum is 49.

The square root of 21499879 is about 4636.7961999639. The cubic root of 21499879 is about 278.0643666840.

The spelling of 21499879 in words is "twenty-one million, four hundred ninety-nine thousand, eight hundred seventy-nine".